scattering light
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2022 ◽  
Author(s):  
Gerson Kniphoff da Cruz

Abstract The arcs of dawn and dusk are natural phenomena that define the boundary of the border between day and night. They are associated with the refraction of solar rays at high angles of incidence that converge to project an arc of light onto the back side of the earth's atmosphere. The rings of dawn and dusk, in turn, are associated with rays, also at large angles of incidence, which converge to project the image of the Sun. Arcs and rings become visible by scattering light by clouds or particles suspended in atmospheric air in the region in which they occur. Here we show a model that describes these natural phenomena and report the first-time record image produced in July of this year.


AIP Advances ◽  
2021 ◽  
Vol 11 (11) ◽  
pp. 115114
Author(s):  
Hongjun Wang ◽  
Yingge Zhang ◽  
Dasen Wang ◽  
Bingcai Liu ◽  
Xueliang Zhu ◽  
...  

2021 ◽  
Author(s):  
Bote Qi ◽  
Lihua Shen ◽  
Rui-pin Chen
Keyword(s):  

2021 ◽  
Author(s):  
Zohreh Hosseinaee ◽  
Ben Ecclestone ◽  
Nicholas Pellegrino ◽  
Layla Khalili ◽  
Lyazzat Mukhangaliyeva ◽  
...  

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Jiamiao Yang ◽  
Qiaozhi He ◽  
Linxian Liu ◽  
Yuan Qu ◽  
Rongjun Shao ◽  
...  

AbstractSpeed and enhancement are the two most important metrics for anti-scattering light focusing by wavefront shaping (WS), which requires a spatial light modulator with a large number of modulation modes and a fast speed of response. Among the commercial modulators, the digital-micromirror device (DMD) is the sole solution providing millions of modulation modes and a pattern rate higher than 20 kHz. Thus, it has the potential to accelerate the process of anti-scattering light focusing with a high enhancement. Nevertheless, modulating light in a binary mode by the DMD restricts both the speed and enhancement seriously. Here, we propose a multi-pixel encoded DMD-based WS method by combining multiple micromirrors into a single modulation unit to overcome the drawbacks of binary modulation. In addition, to efficiently optimize the wavefront, we adopted separable natural evolution strategies (SNES), which could carry out a global search against a noisy environment. Compared with the state-of-the-art DMD-based WS method, the proposed method increased the speed of optimization and enhancement of focus by a factor of 179 and 16, respectively. In our demonstration, we achieved 10 foci with homogeneous brightness at a high speed and formed W- and S-shape patterns against the scattering medium. The experimental results suggest that the proposed method will pave a new avenue for WS in the applications of biomedical imaging, photon therapy, optogenetics, dynamic holographic display, etc.


2021 ◽  
Vol 2021 ◽  
pp. 1-7
Author(s):  
Miao Liu ◽  
Yunyun Mu ◽  
Jingyun Hu ◽  
Jiajun Li ◽  
Xinping Zhang

Detection of low-concentration molecules in liquids has been a challenge in sensing technologies. Raman spectroscopy is an effective approach for trace detection, which is in fact a “volume-excitation” and “volume-collection” technique in the analysis of liquid samples. However, for the commonly employed one-pass excitation and back-scattering detection scheme, a large portion of both the excitation laser energy and the Raman-scattering light energy is wasted without efficient reuse or collection. In this consideration, we demonstrate a broadband optical feedback scheme by a curved high-reflection mirror for both the excitation and the Raman-scattering light, so that the excitation and the forward-propagating Raman signal can be back-reflected and collected with a high efficiency. Using the “F+2f” design, where F and f are the focal lengths of the focusing lens and curved reflection mirror, respectively, we were able to not only produce two focuses of the excitation laser beam but also extend the Raman interaction by a doubled distance. For the detection of pure ethanol molecules and the R6G molecules in water with a concentration of 10−3 M, the Raman signal was enhanced by a factor of about 5.6. The optical feedback scheme and discovered optical mechanisms supply effective improvements to the Raman spectroscopic measurements on liquid samples.


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